Method and apparatus for mechanical and chemical-mechanical planarization of microelectronic substrates with metal compound abrasives

ABSTRACT

A method and apparatus for planarizing a microelectronic substrate. In one embodiment, the apparatus can include a fixed abrasive polishing pad having metal abrasive elements selected to be a compound of metal in the substrate. Alternatively, the metal abrasive elements can include a refractory metal where the substrate includes a refractory metal. Where the substrate includes two metals, the abrasive elements can be selected to planarize the first metal at a rate that is less than approximately twice the rate at which it planarizes the second metal. A single fixed abrasive polishing pad and a single planarizing liquid can be used to planarize both metals.

TECHNICAL FIELD

[0001] The present invention relates to pads having metal and/or metalcompound abrasives for planarizing microelectronic substrates inmechanical and chemical-mechanical planarizing processes.

BACKGROUND OF THE INVENTION

[0002] Mechanical and chemical-mechanical planarizing processes(collectively “CMP”) are used in the manufacturing of microelectronicdevices for forming a flat surface on semiconductor wafers, fieldemission displays and many other microelectronic-device substrates andsubstrate assemblies. FIG. 1 schematically illustrates a CMP machine 10having a platen 20. The platen 20 supports a planarizing medium 40 thatcan include a polishing pad 41 having a planarizing surface 42 on whicha planarizing liquid 43 is disposed. The polishing pad 41 may be aconventional polishing pad made from a continuous phase matrix material(e.g., polyurethane), or it may be a new generation fixed abrasivepolishing pad made from abrasive particles fixedly dispersed in asuspension medium. The planarizing liquid 43 may be a conventional CMPslurry with abrasive particles and chemicals that remove material fromthe wafer, or the planarizing liquid may be a planarizing solutionwithout abrasive particles. In most CMP applications, conventional CMPslurries are used on conventional polishing pads, and planarizingsolutions without abrasive particles are used on fixed abrasivepolishing pads.

[0003] The CMP machine 10 can also include an underpad 25 attached to anupper surface 22 of the platen 20 and the lower surface of the polishingpad 41. A drive assembly 26 rotates the platen 20 (as indicated by arrowA), and/or it reciprocates the platen 20 back and forth (as indicated byarrow B). Because the polishing pad 41 is attached to the underpad 25,the polishing pad 41 moves with the platen 20.

[0004] A wafer carrier 30 is positioned adjacent the polishing pad 41and has a lower surface 32 to which a substrate assembly 12 may beattached via suction. Alternatively, the substrate assembly 12 may beattached to a resilient pad 34 positioned between the substrate assembly12 and the lower surface 32. The wafer carrier 30 may be a weighted,free-floating wafer carrier, or an actuator assembly 33 may be attachedto the wafer carrier to impart axial and/or rotational motion (asindicated by arrows C and D, respectively).

[0005] To planarize the substrate assembly 12 with the CMP machine 10,the wafer carrier 30 presses the substrate assembly 12 face-downwardagainst the polishing pad 41. While the face of the substrate assembly12 presses against the polishing pad 41, at least one of the platen 20or the wafer carrier 30 moves relative to the other to move thesubstrate assembly 12 across the planarizing surface 42. As the face ofthe substrate assembly 12 moves across the planarizing surface 42,material is continuously removed from the face of the substrate assembly12.

[0006] CMP processes should consistently and accurately produce auniformly planar surface on the substrate assembly to enable precisefabrication of circuits and photo-patterns. During the fabrication oftransistors, contacts, interconnects and other features, many substratesdevelop large “step heights” that create a highly topographic surfaceacross the substrate. Yet, as the density of integrated circuitsincreases, it is necessary to have a planar substrate surface at severalstages of processing the substrate because non-uniform substratesurfaces significantly increase the difficulty of forming sub-micronfeatures. For example, it is difficult to accurately focusphoto-patterns to within tolerances approaching 0.1 μm on non-uniformsubstrate surfaces because sub-micron photolithographic equipmentgenerally has a very limited depth of field. Thus, CMP processes areoften used to transform a topographical substrate surface into a highlyuniform, planar substrate surface.

[0007] In the competitive semiconductor industry, it is also highlydesirable to have a high yield in CMP processes by producing a uniformlyplanar surface at a desired endpoint on a substrate assembly as quicklyas possible. For example, when a conductive layer on a substrateassembly is under-planarized in the formation of contacts orinterconnects, many of these components may not be electrically isolatedfrom one another because undesirable portions of the conductive layermay remain on the substrate over a dielectric layer. Additionally, whena substrate is over-planarized, components below the desired endpointmay be damaged or completely destroyed. Thus, to provide a high yield ofoperable microelectronic devices, CMP processing should quickly removematerial until the desired endpoint is reached.

[0008] The planarity of the finished substrate assemblies and the yieldof CMP processing is a function of several factors, one of which is therate at which material is removed from the substrate assembly (the“polishing rate”). Although it is desirable to have a high polishingrate to reduce the duration of each planarizing cycle, the polishingrate should be uniform across the substrate to produce a uniformlyplanar surface. The polishing rate should also be consistent toaccurately endpoint CMP processing at a desired elevation in thesubstrate assembly. The polishing rate, therefore, should be controlledto provide accurate, reproducible results.

[0009] In manufacturing microelectronic substrate assemblies, metalfeatures are typically incorporated into the substrate to electricallyconnect devices and features of the substrate. For example, metal plugscan extend between layers of the substrate assembly to connect portionsof the layers, and metal interconnects can extend from one region of alayer to another to connect features on the same layer. The metalfeatures can include a conductive element surrounded by a diffusionbarrier, each formed from a different metal composition. Duringplanarization, the material forming the conductive element typicallyplanarizes at a faster rate than does the material forming the diffusionbarrier. Accordingly, the conductive element can become “dished”relative to the surrounding diffusion barrier, resulting in an unevensurface topography. As discussed above, an uneven surface typography canmake it difficult to form sub-micron devices.

[0010] One approach to addressing this problem has been to add metaloxide abrasives to the planarizing liquid 43. For example, theplanarizing liquid 43 can include titania abrasive particles toplanarize a substrate assembly 12 having titania diffusion barriers orthe planarizing liquid 43 can include alumina abrasive particles toplanarize a substrate assembly 12 having alumina structures. However,this approach has several drawbacks as well. For example, the polishingrate can be influenced by the distribution of the planarizing liquid 43between the substrate assembly 12 and the planarizing surface 42 of thepolishing pad 41. The distribution of the planarizing liquid 43 may notbe uniform across the surface of the substrate assembly 12 because theleading edge of the substrate assembly 12 can wipe a significant portionof the planarizing liquid 43 from the polishing pad 41 before theplanarizing liquid 43 can contact the other areas of the substrateassembly. The non-uniform distribution of planarizing liquid 43 underthe substrate assembly 12 can cause certain areas of the substrateassembly 12 to have a higher polishing rate than other areas becausethey have more contact with the chemicals and/or abrasive particles inthe planarizing liquid 43. The surface of the substrate assembly 12 mayaccordingly not be uniformly planar, and in extreme cases, some devicesmay be damaged or destroyed by CMP processing.

[0011] The polishing rate may also vary from one substrate assembly toanother, or even across a particular substrate, because the compositionof the planarizing liquid 43 may vary. The chemicals added to theplanarizing liquid 43 may degrade over time causing one batch ofplanarizing liquid 43 to have a different polishing rate than anotherbatch of planarizing liquid 43. Additionally, many components in theplanarizing liquid 43 settle in a liquid solution, and thus theconcentration of chemicals of a particular batch of planarizing liquid43 may also vary. As a result of the changes in the composition of theplanarizing liquid 43, the polishing rate of a particular substrateassembly 12 may change, making it difficult to uniformly planarize thesubstrate assembly 12 and to stop the planarization at a desiredendpoint.

[0012] Another conventional CMP method, used for planarizing a substratehaving two different overlying metals, is to change the planarizingmedium as the first metal is removed and the second metal is exposed.For example, the substrate can be moved from one polishing pad having anabrasivity selected for removing the first metal to another polishingpad having a different abrasivity selected for removing the secondmetal, after the second metal is exposed. Alternatively, the chemicalcomposition of the planarizing liquid can be changed as the second metalis exposed. In this way, the planarizing medium can be tailored to theparticular metal being removed. This approach can have severaldrawbacks. For example, it can be time consuming to move the substratefrom one polishing pad to another, or to change planarizing liquids,thereby reducing the efficiency of the CMP process. Furthermore, thisapproach may not satisfactorily remove the first and second metals whenboth metals are exposed simultaneously. Thus, conventional CMPprocessing may not provide sufficiently planar surfaces or an adequateyield of operable devices.

SUMMARY OF THE INVENTION

[0013] The present invention is directed toward methods and apparatusesfor planarizing microelectronic substrates. In one aspect of theinvention, the apparatus can include a fixed abrasive polishing padhaving fixed abrasive elements that are selected to correspond to ametal in the microelectronic substrate. For example, where themicroelectronic substrate includes a metal such as titanium, thepolishing pad can include a compound of titanium, such as titaniumdioxide. Alternatively, the polishing pad can include a refractory metalwhere the microelectronic substrate includes the same or a differentrefractory metal.

[0014] In another aspect of the invention, the apparatus can include thecombination of a metal-containing microelectronic substrate and a fixedabrasive polishing pad. The substrate can have a metal feature with afirst metal material and a second metal material adjacent to the firstmetal material. The fixed abrasive polishing pad can include asuspension medium having a plurality of abrasive elements that togetherhave a first removal rate of the first metal material and a secondremoval rate of the second metal material such that a ratio of the firstremoval rate to the second removal rate is less than or equal toapproximately two. The metal feature can include an interconnect locatedwithin a selected layer of the substrate, or it can include a conductiveplug that extends between layers of the substrate.

[0015] In a method in accordance with still another aspect of theinvention, a single planarizing liquid and a single polishing pad havingfixed abrasive elements that include a metal compound can be engagedwith a microelectronic substrate to remove metal material from thesubstrate. For example, where the substrate includes a substratematerial with first and second metals, the second metal forming aninterface with the substrate material and the first metal disposed onthe second metal, the method can include engaging the substrate with thesingle polishing pad and the single planarizing liquid to remove boththe first and second metals and expose the substrate material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a partially schematic, partial cross-sectional sideelevation view of a planarizing machine in accordance with the priorart.

[0017]FIG. 2 is a partially cutaway isometric view of a portion of amicroelectronic substrate suitable for planarization in accordance withan embodiment of the invention.

[0018]FIG. 3 is a cross-sectional view of the substrate shown in FIG. 2with conductive materials disposed thereon, taken substantially alongline 3-3 of FIG. 2.

[0019]FIG. 4 is a partially schematic, partial cross-sectional sideelevation view of a planarizing machine having a polishing pad inaccordance with an embodiment of the invention.

[0020]FIG. 5 is a detailed partially schematic cross-sectional sideelevation view partially illustrating the polishing pad shown in FIG. 5,along with an inverted portion of the substrate shown in FIG. 3.

[0021]FIG. 6 is a cross-sectional view of the substrate shown in FIG. 5after planarization in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present disclosure describes methods and apparatuses formechanical and/or chemical-mechanical planarization of substrateassemblies used in the fabrication of microelectronic devices. Manyspecific details of certain embodiments of the invention are set forthin the following description and in FIGS. 2-6 to provide a thoroughunderstanding of the embodiments described herein. One skilled in theart, however, will understand that the present invention may haveadditional embodiments, or that the invention may be practiced withoutseveral of the details described in the following description.

[0023]FIG. 2 is a partially cutaway isometric view of a portion of amicroelectronic substrate 112, which is shown to provide details of theenvironment in which an embodiment of the invention operates. Themicroelectronic substrate 112 can include a substrate material such as asemiconductor or dielectric material having etched surface features 114,shown as a laterally extending trench 114 a and a downwardly extendinghole 114 b. The laterally extending trench 114 a can be filled with aconductive material to provide conductive links between features locatedat the same elevation of the substrate 112. The downwardly extendinghole 114 b can be filled with a conductive material to provide aconductive link between one feature (such as a conductive line orinterconnect 113) located at one elevation of the substrate 112, andother features located at other elevations of the substrate 112.

[0024]FIG. 3 is a cross-sectional side elevation view of the substrate112 shown in FIG. 2 after a diffusion barrier 115 has been disposed onthe walls of the features 114 and a conductive material 116 has beendisposed on the diffusion barrier 115. The diffusion barrier 115 formsan interface with the substrate material that is positioned a distance Dfrom a rear surface 119 of the substrate 112. The diffusion barrier 115can prevent or at least restrict diffusion of the conductive material116 into the substrate 112. Accordingly, the diffusion barrier 115 caninclude materials such as titanium dioxide, titanium nitride, tantalumoxide, tantalum nitride, tungsten, tungsten compounds or other elementsor compounds that prevent or restrict diffusion of the conductivematerial 116. The conductive material 116 provides the conductive linksdiscussed above and can be formed from any conductive metal, such ascopper, aluminum, tungsten or compounds thereof. In one embodiment, theconductive material 116 can include titanium nitride, which has areduced tendency to diffuse into the substrate 112, and the diffusionbarrier 115 can therefore be eliminated.

[0025]FIG. 4 is a partially schematic, partial cross-sectional sideelevation view of a planarizing machine 100 and a polishing pad 141 inaccordance with one embodiment of the invention for planarizing thesubstrate 112. The features and advantages of the polishing pad 141 arebest understood in the context of the structure and the operation of theplanarizing machine 100. Thus, the general features of the planarizingmachine 100 will be described initially.

[0026] The planarizing machine 100 is a web-format planarizing machinewith a support table 110 having a top-panel 111 at a workstation wherean operative portion “A” of the polishing pad 141 is positioned. Thetop-panel 111 is generally a rigid plate that provides a flat, solidsurface to which a particular section of the polishing pad 141 may besecured during planarization. The planarizing machine 100 also has aplurality of rollers to guide, position and hold the polishing pad 141over the top-panel 111. In one embodiment, the rollers include a supplyroller 121, first and second idler rollers 123 a and 123 b, first andsecond guide rollers 124 a and 124 b, and a take-up roller 127. Thesupply roller 121 carries an unused or pre-operative portion of thepolishing pad 141, and the take-up roller 127 carries a used orpost-operative portion of the polishing pad 141. Additionally, the firstidler roller 123 a and the first guide roller 124 a stretch thepolishing pad 141 over the top-panel 111 to hold the polishing pad 141stationary during operation. A motor (not shown) drives the take-uproller 127 and can also drive the supply roller 121 to sequentiallyadvance the polishing pad 141 across the top-panel 111. As such, cleanpre-operative sections of the polishing pad 141 may be quicklysubstituted for worn sections to provide a consistent surface forplanarizing and/or cleaning the substrate 112.

[0027] The planarizing machine 100 also has a carrier assembly 130 totranslate the substrate 112 across the polishing pad 141. In oneembodiment, the carrier assembly 130 has a substrate holder 131 to pickup, hold and release the substrate 112 at appropriate stages of theplanarizing and finishing cycles. The carrier assembly 130 may also havea support gantry 135 carrying a drive assembly 134 that translates alongthe gantry 135. The drive assembly 134 generally has an actuator 136, adrive shaft 137 coupled to the actuator 136, and an arm 138 projectingfrom the drive shaft 137. The arm 138 carries the substrate holder 131via a terminal shaft 139. In another embodiment, the drive assembly 135can also have another actuator (not shown) to rotate the terminal shaft139 and the substrate holder 131 about an axis C-C as the actuator 136orbits the substrate holder 131 about the axis B-B. One suitableplanarizing machine without the polishing pad 141 is manufactured byObsidian, Inc. of Fremont, Calif. In light of the embodiments of theplanarizing machine 100 described above, a specific embodiment of thepolishing pad 141 will now be described in more detail.

[0028]FIG. 5 is a detailed partially schematic cross-sectional sideelevation view partially illustrating the polishing pad 141 according toone embodiment of the invention, positioned over the top-panel 111 ofthe planarizing machine 100 (FIG. 5). The substrate 112 is supported bythe substrate holder 131 in an inverted position over the polishing pad141. In the embodiment shown in FIG. 5, the polishing pad 141 has abacking film 145, a body 144 attached to the backing film 145, and asuspension medium 150 attached to the body 144. The backing film 145 isgenerally a flexible sheet that can wrap around the rollers of theplanarizing machine 100. The backing film 145 also generally has a hightensile strength to withstand the tensile forces exerted on thepolishing pad 141 as an operative section of the polishing pad 141 isstretched over the top-panel 111. One suitable material for the backingfilm 145 is Mylar® manufactured by E. I. Du Pont de Nemours ofWilmington, Del.

[0029] The body 144 of the polishing pad 141 has a backing surface 146and a front surface 148 opposite the backing surface 146. The backingsurface 146 is configured to be attached to the backing film 145, andthe front surface 148 is preferably a highly planar surface facing awayfrom the top-panel 111 to provide an interface surface for thesuspension medium 150. The body 144 is generally composed of acontinuous phase matrix material, such as polyurethane, or othersuitable polishing pad materials. In general, the body 144 is designedto provide the polishing pad 141 with a selected level ofcompressibility/rigidity. Alternatively, the body 144 can be eliminatedand the suspension medium 150 can be attached directly to the backingfilm 145.

[0030] The suspension medium 150 has a planarizing surface 142 facingopposite the backing film 145. In one embodiment, the planarizingsurface can be generally flat and in other embodiments, the planarizingsurface 142 can be textured to improve its performance. In any case, thesuspension medium 150 can include a plurality of abrasive elements 151distributed throughout the suspension medium 150 and adjacent theplanarizing surface 142 for removing material from the substrate 112.Accordingly, the suspension medium 150 can include a binder material,such as an organic resin typically used for fixed abrasive polishingpads. Alternatively, the suspension medium 150 can include othermaterials that fixedly retain the abrasive elements 151.

[0031] The abrasive elements 151 can have a variety of shapes, sizes,compositions and distributions, so long as they effectively planarizethe substrate 112. For example, the abrasive elements 151 can bespherical with a diameter of between approximately 10 nm andapproximately 1000 nm. In one aspect of this embodiment, the abrasiveelements 151 can have a diameter of between approximately 50 nm andapproximately 500 nm. The abrasive elements 151 can be uniformlydistributed throughout the suspension medium 150, or alternatively, theabrasive elements 151 can be concentrated in selected regions of thesuspension medium 150 to locally increase the planarizing rate of thepolishing pad 141.

[0032] In one embodiment, the abrasive elements 151 can be selected suchthat the polishing pad 141 planarizes the conductive material 116 at arate that is less than five times the rate at which the polishing pad141 planarizes the diffusion barrier 115. Accordingly, an embodiment ofthe invention can reduce the tendency for the polishing pad 141 toover-planarize the conductive material 116 relative to the diffusionbarrier 115, when both materials simultaneously contact the polishingpad 141. For example, in one aspect of this embodiment, the polishingpad 141 can include titanium dioxide (titania) abrasive elements 151 andcan planarize a copper conductive material 116 at approximately twicethe rate with which the polishing pad 141 planarizes a titaniumdiffusion barrier 115.

[0033] In a further aspect of this embodiment, the ratio of theconductive material planarizing rate to the diffusion barrierplanarizing rate can be approximately 1:1 by providing a planarizingliquid 143 on the planarizing surface 142 of the polishing pad 141. Theplanarizing liquid 143 can include fluids known to those skilled in theart that chemically enhance the planarizing rate, for example, oxidizingsolutions such as ammonium persulfate, hydrogen peroxide and/or ferricnitrate. Alternatively, the planarizing liquid 143 can include achemical etchant, such as phosphoric acid or oxalic acid. In eithercase, the planarizing liquid can also include a corrosion inhibitor,such as benzotriazole, to halt oxidation or etching once a selectedportion of material has been removed. Accordingly, the planarizingliquid 143 is generally similar to commercially available chemicalslurries, but does not include suspended abrasive particles. In otherembodiments, the planarizing liquid 143 can include other compounds thatcontrol the planarizing rate.

[0034] In still another embodiment, the composition of the abrasiveelements 151 can be selected to be a compound of either the conductivematerial 116 or the material forming the diffusion barrier 115. Forexample, where the diffusion barrier 115 includes titanium, the abrasiveelements 151 can be selected to be a compound of titanium, such astitanium dioxide. Alternatively, the abrasive elements 151 can beselected to include other compounds of the conductive material 116 orthe diffusion barrier 115.

[0035]FIG. 6 is a cross-sectional view of the substrate 112 shown inFIG. 5, after planarization. The conductive material 116 and diffusionbarriers 115 have been planarized down to the distance D from the rearsurface 119 of the substrate 112, exposing a portion of the substratematerial and forming a conductive interconnect 113 a and a conductiveplug 118, each of which has a generally flat upper surface. Accordingly,the substrate 112 can support the formation of sub-micron featuresformed on top of the upper surfaces.

[0036] One feature of polishing pads 141 having abrasive elements 151 inaccordance with the embodiments discussed above is that the ratio of theplanarizing rate of the conductive material 116 to the planarizing rateof the diffusion barrier 115 can be in the range of between about 5:1and about 1:1, and in one aspect of the embodiments, less than or equalto approximately 2:1. Accordingly, the polishing pad 141 will be lesslikely to overplanarize the conductive material 116 relative todiffusion barrier 115, which can result in “dishing” the conductivematerial 116, and which can form a nonplanar surface.

[0037] Another feature of the polishing pads 141 discussed above is thatthe abrasive elements 151 can be fixedly attached to the suspensionmedium 150 to form a fixed abrasive polishing pad. This feature isadvantageous because it can be easier to control the planarizing rate ofthe polishing pad 141 where the abrasive elements 151 are fixedlyattached to the suspension medium 150, as compared to planarizing mediain which the abrasive elements are dispersed in a slurry. Furthermore,the fixed abrasive elements may be less likely to dish the substrate 112than are abrasive elements dispersed in a slurry.

[0038] Still another feature of the polishing pads 141 and theplanarizing liquids 143 is that a single polishing pad 141 and a singleplanarizing liquid 143 can effectively remove both the conductivematerial 116 and enough of the diffusion barrier 115 to expose theunderlying substrate material. An advantage of this feature is thatconductive features, such as the interconnect 113 a and the conductiveplug 118 can be formed without engaging the substrate 112 with twoseparate polishing pads 141, and/or without exposing the substrate 112to two separate planarizing liquids 143, reducing the duration andcomplexity of the planarizing process. Alternatively, the singlepolishing pad 141 can be used in combination with two planarizingliquids, one that preferentially removes the conductive material 116 andanother that preferentially removes the diffusion barrier 115 once thediffusion barrier 115 is exposed. This alternate method can also provideadvantages over some conventional methods because only a singlepolishing pad 141 is necessary to effectively planarize the substrate112.

[0039] From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. For example, although theembodiments of the polishing pad 141 illustrated in FIG. 6 includes abacking film 145, other embodiments of polishing pads in accordance withthe invention do not include a backing film. The embodiments of thepolishing pads shown in FIG. 6 include the backing film 145 because theyare well suited for use with the web-format planarizing machine 100shown in FIG. 2. Other embodiments of the polishing pads having agenerally circular planform shape without the backing film 145 aregenerally suitable for use with rotating platen planarizing machinessimilar to the planarizing machine 10 shown in FIG. 1. Additionally,depending upon the particular CMP application, a planarizing fluid withor without abrasive particles may be used on a polishing pad with orwithout abrasive particles. Accordingly, the invention is not limitedexcept as by the appended claims.

1. A method for planarizing a microelectronic substrate, comprising:selecting the microelectronic substrate to include a first refractorymetal; selecting a composition of a plurality of abrasive particlesdispersed in a polishing pad to include a second refractory metal;engaging the polishing pad and the abrasive particles with the firstrefractory metal of the microelectronic substrate; and moving at leastone of the polishing pad and the microelectronic substrate relative tothe other of the polishing pad and the microelectronic substrate toremove at least a portion of the first refractory metal from themicroelectronic substrate.
 2. The method of claim 1 wherein theselecting the microelectronic substrate to include a first refractorymetal includes selecting the first refractory metal from titanium, atitanium compound, tantalum, a tantalum compound, tungsten and atungsten compound.
 3. The method of claim 1 wherein selecting acomposition of a plurality of abrasive particles dispersed in apolishing pad includes selecting the abrasive particles to includetitanium dioxide.
 4. The method of claim 1 wherein engaging thepolishing pad includes engaging a first portion of the polishing pad,further comprising advancing the polishing pad from a supply roller to atake-up roller to engage a second portion of the polishing pad withanother microelectronic substrate.
 5. The method of claim 1, furthercomprising disposing a planarizing liquid on a planarizing surface ofthe polishing pad while moving at least one of the microelectronicsubstrate and the polishing pad relative to the other to chemicallyremove material from the microelectronic substrate.
 6. The method ofclaim 1, further comprising selecting the abrasive particles to have adiameter of between approximately 10 nm and 1000 nm.
 7. The method ofclaim 1, further comprising selecting the abrasive particles to have adiameter of between approximately 50 nm and approximately 500 nm.
 8. Amethod for planarizing a microelectronic substrate, comprising:selecting a composition of a plurality of abrasive particles dispersedin a polishing pad to include a compound of a metal at a surface of themicroelectronic substrate; engaging the polishing pad and the abrasiveparticles with the metal of the microelectronic substrate; and moving atleast one of the polishing pad and the microelectronic substraterelative to the other of the polishing pad and the microelectronicsubstrate to remove at least a portion of the metal from themicroelectronic substrate.
 9. The method of claim 8 wherein themicroelectronic substrate includes at least one of titanium and atitanium compound and selecting the composition of the plurality ofabrasive particles includes selecting the abrasive particles to includetitanium dioxide.
 10. The method of claim 8 wherein engaging thepolishing pad includes engaging a first portion of the polishing pad,further comprising advancing the polishing pad from a supply roller to atake-up roller to engage a second portion of the polishing pad withanother microelectronic substrate.
 11. The method of claim 8 whereinmoving at least one of the microelectronic substrate and the polishingpad includes orbiting the microelectronic substrate relative to thepolishing pad.
 12. The method of claim 8, further comprising disposing aplanarizing liquid on a planarizing surface of the polishing pad whilemoving at least one of the microelectronic substrate and the polishingpad relative to the other to chemically remove material from themicroelectronic substrate.
 13. The method of claim 12 wherein the metalof the microelectronic substrate is a first metal, the microelectronicsubstrate having a second metal adjacent the first metal, furtherwherein disposing a planarizing liquid includes disposing a singleplanarizing liquid to chemically remove both the first metal and thesecond metal.
 14. The method of claim 12 wherein the metal of themicroelectronic substrate is a first metal, the microelectronicsubstrate having a second metal adjacent the first metal, furtherwherein disposing a planarizing liquid includes disposing a firstplanarizing liquid to chemically remove the first metal, furthercomprising disposing a second planarizing liquid on the planarizingsurface of the polishing pad to chemically remove the second metal. 15.The method of claim 12, further comprising selecting the planarizingliquid to include at least one of an oxidizing agent, an etchant and acorrosion inhibitor.
 16. The method of claim 8, further comprisingselecting the abrasive particles to have a diameter of betweenapproximately 10 nm and 1000 nm.
 17. The method of claim 8, furthercomprising selecting the abrasive particles to have a diameter ofbetween approximately 50 nm and approximately 500 nm.
 18. The method ofclaim 8, further comprising selecting the abrasive particles to have agenerally spherical shape.
 19. A method for planarizing amicroelectronic substrate, comprising: selecting the microelectronicsubstrate to have a first portion that includes copper and/or aluminumand a second portion that includes at least one of titanium, a titaniumcompound, tantalum, a tantalum compound, tungsten and a tungstencompound; selecting a polishing pad to have a plurality of abrasiveelements therein, the abrasive elements including a titanium compound;engaging the polishing pad and the abrasive elements with the first andsecond portions of the microelectronic substrate; and moving at leastone of the polishing pad and the microelectronic substrate relative tothe other of the polishing pad and the microelectronic substrate toremove at least some of the first and second portions from themicroelectronic substrate.
 20. The method of claim 19, furthercomprising selecting the abrasive elements to include titanium dioxide.21. The method of claim 19 wherein moving at least one of themicroelectronic substrate and the polishing pad includes rotating thepolishing pad relative to the microelectronic substrate.
 22. The methodof claim 19 wherein moving at least one of the microelectronic substrateand the polishing pad includes orbiting the microelectronic substraterelative to the polishing pad.
 23. The method of claim 19, furthercomprising disposing a planarizing liquid on a planarizing surface ofthe polishing pad while moving at least one of the microelectronicsubstrate and the polishing pad relative to the other to chemicallyremove material from the microelectronic substrate.
 24. The method ofclaim 19, further comprising selecting the abrasive elements to have adiameter of between approximately 10 nm and 1000 nm.
 25. The method ofclaim 19, further comprising selecting the abrasive elements to have adiameter of between approximately 50 nm and approximately 500 nm. 26.The method of claim 19, further comprising selecting the abrasiveelements to have a generally spherical shape.
 27. The method of claim 19wherein engaging the polishing pad includes engaging a first portion ofthe polishing pad, further comprising advancing the polishing pad from asupply roller to a take-up roller to engage a second portion of thepolishing pad with another microelectronic substrate.
 28. A method forplanarizing a microelectronic substrate that includes a substratematerial, a first metal material and a second metal material differentthan the first metal material, the substrate having a first surface anda second surface opposite the first surface with the second metalmaterial disposed on the first surface of the substrate material todefine at least one interface at a selected distance from the secondsurface of the substrate material, and the first metal material disposedon the second metal material, the method comprising: engaging themicroelectronic substrate with a planarizing liquid; removing at least aportion of the first metal material by engaging the microelectronicsubstrate with a fixed abrasive polishing pad having a plurality ofabrasive elements that include a metal compound and moving at least oneof the polishing pad and the microelectronic substrate relative to theother; and removing approximately all of the second metal material atthe one interface by continuing to engage the microelectronic substratewith the same fixed abrasive polishing pad and the same planarizingliquid to expose the substrate material at the one interface.
 29. Themethod of claim 28 wherein removing the first metal material includesremoving the first metal material at a first rate and removing thesecond metal material includes removing the second metal material at asecond rate such that a ratio of the first rate to the second rate isless than or equal to approximately two.
 30. The method of claim 28wherein removing the first metal material includes removing materialfrom an interconnect in a selected layer of the microelectronicsubstrate and removing the second metal material includes removingmaterial from a diffusion barrier disposed around the interconnect. 31.The method of claim 28 wherein removing the first metal materialincludes removing material from a conductive plug extending from aconductive layer of the microelectronic substrate and removing thesecond metal material includes removing material from a diffusionbarrier disposed around the conductive plug.
 32. The method of claim 28wherein removing the first metal material includes engaging the firstmetal material with abrasive elements that include a titanium compound.33. The method of claim 28 wherein the first metal material includescopper and the second metal material includes a first refractory metal,further wherein engaging the microelectronic with a fixed abrasivepolishing pad includes engaging the microelectronic substrate withabrasive particles that include a second refractory metal.
 34. Themethod of claim 33, further comprising selecting the second refractorymetal to be an oxide of the first refractory metal.
 35. The method ofclaim 28 wherein engaging the microelectronic substrate with a fixedabrasive polishing pad includes engaging the microelectronic substratewith abrasive elements having a diameter of between approximately 10 nmand approximately 1000 nm.
 36. The method of claim 28 wherein engagingthe microelectronic substrate with a fixed abrasive polishing padincludes engaging the microelectronic substrate with abrasive elementshaving a diameter of between approximately 50 nm and approximately 500nm.
 37. The method of claim 28, further comprising selecting theplanarizing liquid to include at least one of an oxidizing agent, acorrosion inhibitor and an etchant.
 38. A method for planarizing amicroelectronic substrate having a first metal material and a secondmetal material adjacent the first metal material, the method comprising:removing the first metal material from the microelectronic substrate ata first rate by engaging the microelectronic substrate with a fixedabrasive polishing pad having a plurality of abrasive elements andmoving at least one of the microelectronic substrate and the fixedabrasive polishing pad relative to the other of the microelectronicsubstrate and the fixed abrasive polishing pad; and engaging themicroelectronic substrate with the fixed abrasive polishing pad andmoving at least one of the microelectronic substrate and the polishingpad relative to the other to remove the second metal material from themicroelectronic substrate at a second rate such that a ratio of thefirst rate to the second rate is less than or equal to approximatelytwo.
 39. The method of claim 38 wherein moving at least one of themicroelectronic substrate and the polishing pad includes rotating thepolishing pad relative to the microelectronic substrate.
 40. The methodof claim 38 wherein engaging the microelectronic substrate with thefixed abrasive polishing pad includes engaging the microelectronicsubstrate with a first portion of the polishing pad, further comprisingadvancing the polishing pad from a supply roller to a take-up roller toengage a second portion of the polishing pad with anothermicroelectronic substrate.
 41. The method of claim 38 wherein removingthe first metal material includes removing material from an interconnectin a selected layer of the microelectronic substrate and removing thesecond metal material includes removing material from a diffusionbarrier disposed around the interconnect.
 42. The method of claim 38wherein removing the first metal material includes removing materialfrom a conductive plug extending from a conductive layer of themicroelectronic substrate and removing the second metal materialincludes removing material from a diffusion barrier disposed around theconductive plug.
 43. The method of claim 38 wherein removing the firstmetal material includes engaging the first metal material with abrasiveelements that include a titanium compound.
 44. The method of claim 38,further comprising disposing a planarizing liquid on a planarizingsurface of the polishing pad while moving at least one of themicroelectronic substrate and the polishing pad relative to the other ofthe microelectronic substrate and the polishing pad to chemically removematerial from the microelectronic substrate.
 45. The method of claim 38wherein the first metal material includes copper and the second metalmaterial includes one of titanium and a titanium compound, furtherwherein engaging the microelectronic with a fixed abrasive polishing padincludes engaging the microelectronic substrate with abrasive particlesthat include a titanium compound.
 46. The method of claim 38 whereinengaging the microelectronic substrate with a fixed abrasive polishingpad includes engaging the microelectronic substrate with abrasiveelements having a diameter of between approximately 10 nm andapproximately 1000 nm.
 47. The method of claim 38 wherein engaging themicroelectronic substrate with a fixed abrasive polishing pad includesengaging the microelectronic substrate with abrasive elements having adiameter of between approximately 50 nm and approximately 500 nm. 48.The combination of a metal-containing substrate and a fixed abrasivepolishing pad, comprising: a microelectronic substrate having a featurewith a first metal material having a first composition and a secondmetal material adjacent to the first metal material having a secondcomposition different than the first composition; a fixed abrasivepolishing pad that includes a suspension medium having a planarizingsurface for planarizing the microelectronic substrate; and a pluralityof abrasive elements distributed in the suspension medium proximate tothe planarizing surface, the suspension medium and the abrasive elementstogether having a first removal rate of the first metal material whenthe suspension medium is engaged with the microelectronic substrate andat least one of the microelectronic substrate and the suspension mediumis moved relative to the other, the suspension medium and the abrasiveelements together having a second removal rate of the second metalmaterial when the suspension medium body is engaged with themicroelectronic substrate and at least one of the microelectronicsubstrate and the suspension medium is moved relative to the other, aratio of the first removal rate to the second removal rate being lessthan or equal to approximately two.
 49. The combination of claim 48wherein the abrasive elements are selected from titanium and a titaniumcompound.
 50. The combination pad of claim 48 wherein the abrasiveelements are selected to include titanium dioxide.
 51. The combinationof claim 48 wherein the first metal material of the feature is copper,the second metal material of the feature is selected from titanium and atitanium compound, and the abrasive elements are selected from atitanium compound.
 52. The combination of claim 48 wherein a material ofthe abrasive elements is selected to be an oxide of one of the first andsecond metal materials.
 53. The combination of claim 48 wherein theabrasive elements have a diameter of between approximately 10 nm andapproximately 1000 nm.
 54. The combination of claim 48 wherein theabrasive elements have a diameter of between approximately 50 nm andapproximately 500 nm.
 55. The combination of claim 48 wherein theabrasive elements have a generally spherical shape.
 56. The combinationof claim 48 wherein the abrasive elements are uniformly distributed inthe suspension medium.
 57. The combination of claim 48 wherein thepolishing pad includes polyurethane.
 58. The combination of claim 48wherein the suspension medium includes an organic resin material. 59.The combination of claim 48 wherein the suspension medium has agenerally circular planform shape for mounting to a generally circularplaten.
 60. The combination of claim 48 wherein the suspension mediumincludes an elongated flexible web configured to be wound from a firstroller across a platen to a second roller.
 61. The combination of claim48 wherein the first metal material forms an interconnect in a selectedlayer of the microelectronic substrate and the second metal materialforms a liner disposed at least partially around the interconnect. 62.The combination of claim 48 wherein the first metal material forms aconductive plug extending from a conductive layer of the microelectronicsubstrate and the second metal material forms a liner disposed at leastpartially around the conductive plug.
 63. The combination of a substrateand a fixed abrasive polishing pad, comprising: a microelectronicsubstrate having a metal feature with a first metal composition; a fixedabrasive polishing pad having a suspension medium with a planarizingsurface for planarizing the microelectronic substrate; and a pluralityof abrasive elements positioned in the suspension medium adjacent theplanarizing surface wherein at least some of the abrasive elementsinclude a metal having a second metal composition that includes acompound of the first metal composition.
 64. The combination of claim 63wherein the first metal composition includes one of titanium and atitanium compound, further wherein the second metal composition isselected to include one of titanium and titanium dioxide.
 65. Thecombination of claim 63 wherein the abrasive elements are uniformlydistributed in the suspension medium.
 66. The combination of claim 63wherein a material of the abrasive elements is selected to be an oxideof the first metal composition.
 67. The combination of claim 63 whereinthe abrasive elements have a diameter of between approximately 10 nm andapproximately 1000 nm.
 68. The combination of claim 63 wherein theabrasive elements have a diameter of between approximately 50 nm andapproximately 500 nm.
 69. The combination of claim 63 wherein theabrasive elements have a generally spherical shape.
 70. The combinationof claim 63 wherein the suspension medium includes an organic resinmaterial.
 71. The combination of claim 63 wherein the suspension mediumhas a generally circular planform shape for mounting to a generallycircular platen.
 72. The combination of claim 63 wherein the suspensionmedium includes an elongated flexible web configured to be wound from afirst roller across a platen to a second roller.
 73. A fixed abrasivepolishing pad for planarizing a microelectronic substrate, comprising: asuspension medium having a planarizing surface for engaging andplanarizing the microelectronic substrate; and a plurality of abrasiveelements distributed in the suspension medium proximate to theplanarizing surface, at least some of the abrasive elements beingselected from a titanium compound.
 74. The polishing pad of claim 73wherein the abrasive elements include titanium dioxide.
 75. Thepolishing pad of claim 73 wherein the abrasive elements are uniformlydistributed in the suspension medium.
 76. The polishing pad of claim 73wherein the abrasive elements have a diameter of between approximately10 nm and approximately 1000 nm.
 77. The polishing pad of claim 73wherein the abrasive elements have a diameter of between approximately50 nm and approximately 500 nm.
 78. The polishing pad of claim 73wherein the abrasive elements have a generally spherical shape.
 79. Thepolishing pad of claim 73 wherein the suspension medium includes anorganic resin material.
 80. The polishing pad of claim 73 wherein thesuspension medium has a generally circular planform shape for mountingto a generally circular platen.
 81. The polishing pad of claim 73wherein the suspension medium includes an elongated flexible webconfigured to be wound from a first roller across a platen to a secondroller.